Description

The ignore flag indicates that an element should be ignored when retrieving values at form level. (row: 694 in Element.php [Zend_Form_Element]).

Since one, as far as I know, almost never use the value of an input/button this would be a good default value.
Makes it easier to run $row->setFromArray($form->getValues()); since MySQL complains about the non-existing column for the button/submit otherwise.